epub2pdf: title-based export names, .pdf download headers, security hardening (68 tests green)

tests/test_fidelity.py

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+"""Text-fidelity regression tests: em dashes and CJK must survive
+EPUB -> WeasyPrint -> pypdf merge without mojibake.
+
+Markers below were verified against test_book.epub ground truth:
+the source contains 3 em dashes and the CJK runs listed in CJK_MARKERS.
+These tests lock in the UTF-8 HTML-string decoding fix (app.py L258-265):
+passing decoded text (not file paths) to WeasyPrint prevents Latin-1
+sniffing from turning em dashes/CJK into mojibake.
+"""
+import io
+
+from pypdf import PdfReader
+
+from tests.helpers import download_bytes, pdf_metadata_title, wait_for_job
+
+EM_DASH = "\u2014"
+CJK_MARKERS = ["中文测试段落", "天地玄黄", "宇宙洪荒", "日月盈昃", "辰宿列张"]
+EXPECTED_TITLE = "Structured Test Book"
+EXPECTED_AUTHOR = "Agent Zero"
+
+
+def _converted_pdf(client, submit_epub):
+    job_id = submit_epub(filename="book.epub").get_json()["job_id"]
+    job = wait_for_job(client, job_id)
+    assert job["status"] == "done", job
+    return download_bytes(client, job["filename"]), job
+
+
+def test_em_dashes_survive_conversion(client, submit_epub):
+    data, _ = _converted_pdf(client, submit_epub)
+    reader = PdfReader(io.BytesIO(data))
+    full = "\n".join((p.extract_text() or "") for p in reader.pages)
+    assert EM_DASH in full, "em dash missing from PDF text"
+    assert full.count(EM_DASH) >= 3, f"expected >=3 em dashes, got {full.count(EM_DASH)}"
+
+
+def test_cjk_text_survives_conversion(client, submit_epub):
+    data, _ = _converted_pdf(client, submit_epub)
+    reader = PdfReader(io.BytesIO(data))
+    full = "\n".join((p.extract_text() or "") for p in reader.pages)
+    for marker in CJK_MARKERS:
+        assert marker in full, f"CJK marker {marker!r} missing from PDF text"
+
+
+def test_no_latin1_mojibake(client, submit_epub):
+    """Mojibake regression: em dash mis-decoded as Latin-1 reads 'â€"'."""
+    data, _ = _converted_pdf(client, submit_epub)
+    reader = PdfReader(io.BytesIO(data))
+    full = "\n".join((p.extract_text() or "") for p in reader.pages)
+    assert "â€" not in full, "Latin-1 mojibake detected for em dash"
+    assert "ï¼" not in full, "CJK fullwidth colon mojibake detected"
+
+
+def test_pdf_metadata_round_trip(client, submit_epub):
+    data, _ = _converted_pdf(client, submit_epub)
+    assert pdf_metadata_title(data) == EXPECTED_TITLE
+    reader = PdfReader(io.BytesIO(data))
+    assert reader.metadata["/Author"] == EXPECTED_AUTHOR
+
+
+def test_page_count_matches_fixture(client, submit_epub):
+    """The 6-page fixture must not silently drop or merge chapters."""
+    data, _ = _converted_pdf(client, submit_epub)
+    reader = PdfReader(io.BytesIO(data))
+    assert len(reader.pages) == 6